The present invention refers to a rope ascender device and to a method for use thereof by an operator.
Motorized devices that allow hoisting oneself, i.e. ascend, along a rope stretched vertically and fixed to a raised anchoring point are available in the market. Generally, the ascending devices referred to comprise a pulley and the respective actuation motor, which may be electric or of the internal combustion type. The seat for the rope obtained on the circumference of the pulley has, in cross-section, a rounded U-shape to allow maximum external surface of the rope to grip. Usually, the motor, with the corresponding battery or fuel tank, is fixed to a small framework having handles directly graspable by the user and rings for anchoring to a harness worn by the user himself. Once fixed onto the device, the user actuates the motor for winding—at least partly—the rope onto the pulley, causing vertical ascension thereof along the rope alongside the device itself.
The ascension controlled by motorized devices is often provided for in the mountain or well rescue operations, or in maintenance and inspection operations on pylons and generally in situations wherein there arises the need to hoist oneself vertically on a stretched rope, without effort. For example, motorized ascender devices are usually used by wind energy generators maintenance technicians for inspecting the blades or hoisting themselves onto the nacelle of the generators.
It is also known that such devices may also be used for hoisting people together with loads of material or equipment.
For example, a motorized ascender device is described in the European patent EP 1030726B1 granted to the Swedish company Act Safe Systems AB. Such device comprises a motor whose driving shaft is coupled to a pulley onto which the rope used for ascending is partly wound, or is wound without completing a loop, for example a half turn. The device further comprises a framework onto which a carabiner or closed ring is prearranged, positioned in proximity to the pulley. In the operative mode of the device, the rope is prearranged by the user in such a manner to pass through the carabiner, be wound around the pulley and pass through the same carabiner again. This configuration guarantees correct winding of the rope onto the pulley and hinders disengagement. The user controls the motor by means of a button to rotate the pulley in the winding direction on the rope, causing the raising of the device and the user secured thereto. The carabiner (or ring) is configured as a forced and closed passage for the rope both upstream and downstream of the pulley with respect to the winding direction. As a matter of fact, once inserted into the carabiner, the rope can no longer exit from the same and it is forced to wind around the pulley correctly.
Adjusting the direction of rotation of the pulley allows controlling not only the ascent but also the descent along the rope. In practice, the ascender device also serves as a motorized descender.
The presence of only one forced and closed passage upstream and downstream of the pulley, forces the rope to be wound on the pulley by half turn. The weight of the same device generates friction between the rope and the pulley, that is enough to hinder the respective sliding between these elements. This allows preventing inadvertent falling of the device and the respective user along the rope, due to the force of gravity, when the device is inoperative, i.e. when the pulley is stationary. In the operative mode described above, with the pulley stationary, the device is configured as an alpine descender of the passive type, i.e. a device that allows descending only if the user intervenes actively on the device, and in the specified example if the user commands the rotation of the pulley in the direction opposite to the ascension one.
Another ascender device having a pulley is described in the International patent application WO 2006/074250. In this embodiment, the pulley may support three turns at most; a forced passage for the rope upstream of the pulley and guide rollers of the rope are provided for on the pulley. The number of turns cannot be modified, in particular when the device is in use.
The devices described above, having a pulley, reveal some drawbacks. The main drawback is related to the low weight that these devices allow to be hoisted, determined by the fact that the winding of the rope around the pulley is shorter than a single turn, i.e. it is limited to less than a complete loop, or it is limited to two or three turns, corresponding to the number of special guide grooves present on the pulley. This configuration has a negative impact also on the wear of the rope.
Another drawback lies in the fact that should the motor fail to function (breakdown, lack of fuel or low battery), the ascender devices of the prior art do not allow the user to ascend. In this case, the user is forced to return to the ground, and in case of emergency the user might be forced to leave the device, which remains suspended, and use alpine descenders applied to the rope. International patent application number WO 2006/113844 describes a powered rope ascender device, provided with a winding drum of the rope in turns parallel and having constant diameter. The device comprises an eyelet for guiding the rope upstream of the winding drum and a return pulley which aligns the rope with respect to the winding drum. The eyelet is configured as a forced passage for the rope. A lever is pivoted to the body of the device and is provided with a series of guide rollers oriented with the respective rotational axis orthogonal to the axis of the drum. The lever is rotatable between a non-operative position, wherein the rollers are distant from the winding drum, and an operative position, wherein the rollers are substantially in abutment against the outer surface of the drum. When the lever is at the non-operative position, the rope may be positioned on the drum; by moving the lever to the operative position, the windings of the rope remain separate from each other, guided by the rollers, and they cannot move along the axis of the drum. The lever comprises a final roller oriented with the respective rotational axis parallel to the axis of the winding drum. The final roller has the task of compressing the exit end of the rope against the winding drum to exert tension sufficient to attain the grip of the turns of the same rope against the drum and, thus, to allow the operation of the ascender device without the rope slipping. The final roller compresses the rope only when the lever is blocked at the operative position thereof.
The device described in the patent application WO 2006/113844 does not allow modifying the configuration of the turns of the rope when the user is hoisted on the same or to slow the descent with the motor off—hence increasing the tension applied at the exit end of the rope —unless by using the hands. When the device is in use, the user cannot rotate the lever to the non-operative position to modify the number of turns (for example adding other turns on the winding drum) in that there would lack the minimum tension required to avoid the sliding of the turns on the drum. In other words, the rotation of the lever in the non-operative position would cause the fall of the user. Another drawback of this device lies in the fact that the structure thereof is complex. Furthermore, the initial position of the turns on the winding drum requires attention by the user, who should arrange the turns spaced for the insertion of the guide rollers therebetween.
Also available in the market are powered pulling devices serving to move loads, but not people, fixed to a rope, vertically or along slanting or uneven surfaces, for example along steep hills. The respective operation provides for anchoring against external structures, for example trees, poles, platforms, etc. and the return of the rope onto which the loads are secured. Generally, such devices are similar to those described previously, but instead of the pulley they are provided with a pulling drum, externally smooth and substantially cylindrical, around which the rope must be wound in several turns. With respect to a pulley, the drum is extended further along the respective rotational axis to allow the winding of at least one complete turn of the rope and preferably allow the winding of several turns in succession.
In particular, in the operative configuration of the pulling devices, the section of the rope under tension is guided by a hook positioned upstream of the drum with respect to the pulling direction, and it is wound in turns on the drum; the section of the rope not under tension leaves the drum substantially free or guided by a second hook, and it is guided manually by the user. The hook does not represent a forced and closed passage for the rope which may be easily disengaged if not guided correctly by the user.
Disadvantageously such devices, used always anchored to fixed structures, are not suitable for hoisting people in that in order to control the descent the user is required to manually exert a tension on the section of the rope coming out from the drum, i.e. the section not under tension comprised between the drum and the underlying ground; in other words the user is required to constantly hold the end of the rope coming out from the drum and apply at least a slight tension, to allow the rope to obtain grip onto the drum and to prevent sliding thereof. This event would lead to a non-controlled descent of the device and the user, with apparent risks for the safety of the user. Due to the need of a manual intervention of the user, the pulling devices would be configured as descenders of the active type, less safe with respect to the devices of the passive type and thus not used for hoisting people. Furthermore, such pulling devices are cumbersome and heavy, thus not suitable to be hoisted together with the user.
The ascender or pulling devices described above are prearranged to operate with ropes of the fabric type but not steel cables, which normally need to be gathered on the drum. In other known pulling devices, the rope of the fabric type or an equivalent steel cable are entirely wound on the pulling drum. Also these devices are not suitable for hoisting people, in that the drums have large dimensions.
The technical problem on which the present invention is based is that of providing an ascender device capable of being used also for pulling loads and such device being safe, simple and efficient under any condition of use and capable of allowing easily adjusting the tension that operates on the rope during ascent and descent.
Another technical problem is that of providing an ascender device of the aforedescribed type, capable of offering maximum comfort for the user.